This invention relates generally to automatic palletizers or depalletizers and more specifically to apparatus that is employed to retain individual slip sheets on top of pallets as the pallets are fed to a loading or unloading position.
The use of pallets on which to stack products to be shipped has long been common practice in industry. The pallets are generally made from wood of varying height and have openings which permit forklifts to extend their forks through to lift an entire load. The product or objects to be shipped are stacked or appropriately placed on top of the pallet.
Automation in manufacturing production lines has led to the development of automatic palletizers. These machines feed pallets automatically from a stack of pallets in a pallet feed rack onto a conveyor which carries the pallets to the loading point. The dispensing of the pallets along the conveyor is a stepped and timed sequence to correspond to the availability of product or material being stacked upon the pallets. The loaded pallets are discharged from the palletizer and then removed, generally by a forklift, to a shipping location where the pallets and the product are loaded onto the appropriate means of transportation, such as a truck or railroad car.
Where pallets are used as an intermediate support for the product that is to be repackaged, shipped on slip sheets without pallets, or moved again prior to placement on the final shipping means, slip sheets or pieces of cardboard or other material of predetermined thickness are placed on top of the pallets. The slip sheets permit the product to be removed more easily from the top of the pallet without damaging either the product containers or the pallets. They also can provide the final shipping base for use with specially modified forklifts and unitized loads, such as in unitized loads where stretch wrapping, banding or gluing is employed. This unitized loading technique reduces shipping freight costs and the number of costly pallets required. However, in an automatic palletizer there has been no apparatus to hold a slip sheet in place on top of the pallet as the pallet moves along its predetermined path on the palletizer conveyor toward the loading point. This and other problems are solved in the design of the apparatus comprising the present invention by employing means to retain a slip sheet in position on top of a pallet.